If the story of Big Star, one of the greatest American rock ‘n’ roll bands of the 1970s — or any other era, for that matter — isn’t familiar to you, here’s your chance to catch up.

The new documentary “Nothing Can Hurt Me” chronicles the Big Star saga from ultra-promising beginning to bitter end. It tells how former Box Tops lead singer Alex Chilton hooked up with Memphis mates Chris Bell, Jody Stephens and Andy Hummel to record the eye-poppingly excellent “#1 Record,” a critical favorite that didn’t sell much in 1972.

Bell left, and the band recorded as a trio for 1974’s “Radio City,” which was clangier, more raucous and more spectacular than its predecessor, and it remains one of the best power-pop albums ever recorded.

But it seemed that the better they got, the less success they had. One more album, the stark “Third/Sister Lovers,” was recorded with Chilton and Stephens, but it wasn’t released until 1978, long after the band’s breakup.

“Nothing Can Hurt Me” is a generous 21-cut soundtrack to the film that contains alternate takes, remixes and demos of most of the band’s best songs, and it easily retains the spark of joy that lifted Big Star’s music, even with the new sonic details popping out from time to time in these versions. (Well, the differences stand out to someone who has played the originals hundreds of times since the early 1970s, anyway.)

You may think you don’t know this material, but if you’ve ever watched “That ’70s Show,” you’ve heard Cheap Trick’s inferior version of “In The Street” over the opening credits. It sounds rushed and exaggerated compared to the Big Star original, heard here in a slightly different take.

Or perhaps you’ve heard one of the umpteen covers of “September Gurls” (none matching the original), the band’s bittersweet jangle-pop anthem that’s anchored by two of the most spine-tingling guitar solos ever recorded.

That still leaves plenty to discover. The alternate version of “Way Out West” is a revelation, clearer, cleaner and slightly slower than the original, with more ache and harder-edged guitar clusters. “Thirteen” sounds much like the original, its gorgeous harmonies, innocence and quintessential teenage sentiments still stunning after all these years. Only its acoustic guitar interludes differ.

Studio chatter, ambient background noises and the occasional unpolished spots along the way add to the fascination of hearing a band discovering its own brilliance.

Do yourself a favor: see the film, get this soundtrack (which was released earlier this year in vinyl form on Record Store Day), and don’t stop until you’ve also acquired all the albums in their original form. They are beyond essential.

The film “Nothing Can Hurt Me” will screen at the Nuart Theatre in West Los Angeles on Friday and Saturday, with special six-song sets by last surviving band member Stephens with members of the Posies at 8:10 both nights.

Sam Gnerre has worked for the Daily Breeze in Torrance since 1984. He grew up in Fontana, Calif., and is a graduate of Fontana High School. He earned a B.A. in English literature from the University of California, Riverside, and a Master's degree in library science from UCLA. He was hired at the Daily Breeze in 1984 to help with the conversion of the paper's manual clip file system to an online database of archived stories. Currently, he writes the paper's weekly News Quiz, does a weekly music CD review, and researches and writes local history articles for the South Bay History blog, in addition to his current duties as a night website editor for the Southern California News Group.